The present invention relates to endoscope apparatus and devices for illuminating viewing objectives which are being viewed through endoscope apparatus. More particularly, the present invention relates to endoscopic viewing objective illumination devices which conduct illumination light from a light source at the viewing end of an endoscope apparatus cable to the image forming end of the cable through illumination light conducting optical fibers. Most particularly, the present invention relates to the geometric configuration of such illumination light conducting fibers in proximity to the image forming end of the cable of an endoscope apparatus.
Fiber-optic endoscopic viewing systems are now in common use in industrial and medical applications. The use of endoscopic equipment has become commonplace in locksmithing and other industrial applications to allow otherwise hidden mechanical components to be viewed and manipulated. Endoscopic surgical and exploratory procedures are steadily replacing more traditional invasive surgical procedures in contemporary medical practice.
Generally, objects and scenes which are the viewing objective of fiber-optic endoscopic viewing systems are typically in very poorly illuminated or totally dark environments and illumination of the viewing objective must be provided to allow it to be readily observed through the endoscope. Fiber-optic viewing systems of the prior art have utilized flexible, light conducting fiber elements within the endoscope cable to conduct illumination light from a high power light source, such as an incandescent or arc lamp, located at the viewing end of the cable to the distal imaging end of the cable. Typically, each of the illumination light conducting fibers lies adjacent to a central fiber-optic image bundle of the cable with its illumination light conducting fiber axis running generally in set apart parallel relation to the coinciding axes of the endoscope cable and image bundle over the entire length of the endoscope cable. The polished, light emitting end face of each of the illumination light conducting fibers is generally normal to all three axes.
This geometric arrangement of the prior art apparatus does not provide complete and uniform illumination of the viewing field of the image forming device of the fiber-optic image bundle at the image forming end of the endoscope cable. Such image forming devices generally have a conically shaped viewing field expanding with distance from the image forming end of the cable at about a 45 to 50 degree angle to the central cable end axis while light emitted from the face of each of the illumination light conducting fibers is concentrated in a conically shaped illumination field expanding with distance from the end of the fiber at about a 20 degree angle to the central illumination light conducting fiber end axis. Thus, the entire viewing field may not be utilized in viewing distant viewing objectives for lack of sufficient illumination of the viewing objective in the outer portion of the viewing field. Further, the overlapping illumination fields of the illumination light conducting fibers results in nonuniform illumination of the viewing objective within the area of sufficient illumination within the viewing field, most particularly varying with radial distance from the center of the viewing field. Typically, an annular shaped area of relatively intense light is created about the center of the view field.
Some endoscopic viewing systems of the prior art have attempted to mitigate these problems by twisting the distal, image forming end of the endoscope apparatus cable such that the center of the illumination field of each of the illumination light conducting fibers angels outwardly along a chord of the cable cross section at an angle to the cable centerline. While this creates some diffusion of the viewing field illumination, all of the conical illumination fields of the illumination light conducting fibers are displaced at equal angles and an annular area about the center of the view field will still be more intensely illuminated than the rest of the field. Further, constructing an endoscope cable of this configuration is a difficult process.
Other endoscopic viewing systems of the prior art have attempted to mitigate these problems by the placement of small, domed lenses on the light emitting ends of the illumination light conducting fibers. Such lenses may be formed in place by placement of drops of transparent epoxy on the light emitting end surfaces of the fibers. While some diffusion of the illumination light is achieved by these systems, a more intensely illuminated annular area will still exist about the center of the view field.
It is an object of the present invention to provide view objective illumination for an endoscope apparatus utilizing flexible, light conducting fiber elements within an endoscope cable to conduct illumination light from the image viewing end of the cable to the image forming end, which will provide illumination of the entire viewing field
It is an object of the present invention to provide view objective illumination for an endoscope apparatus utilizing flexible, light conducting fiber elements within an endoscope cable to conduct illumination light from the image viewing end of the cable to the image forming end, which will provide generally uniform illumination of the view objective along a radius of the viewing field.
It is a further object of the present invention to provide view objective illumination for an endoscope apparatus utilizing flexible, light conducting fiber elements within an endoscope cable to conduct illumination light from the image viewing end of the cable to the image forming end, which will provide uniform illumination of the view objective.
In keeping with the above objectives, an endoscope apparatus comprising a preferred embodiment of the present invention includes an endoscope cable with an image viewing end, and an image forming end with an image forming device. A fiber-optic image bundle extends from the image forming device to the image viewing end of the cable. Sixteen illumination light conducting fiber elements run generally adjacent to, and at equally spaced radial intervals about, the optical-fiber image bundle over the length of the endoscope cable. A light source at the image viewing end of the cable provides light which is conducted by the illumination light conducting fiber elements from the image viewing end of the endoscope cable to the image forming end of the cable where the light is emitted through end faces of the illumination light conducting fiber elements to radiate upon and illuminate the view objective. At the image forming end portion of the endoscope cable, the cable, image forming device and fiber optic image bundle have a common axis including a common image forming end portion axis. Each of the illumination light conducting fiber elements has a central axis including an image forming end portion axis. Four of the illumination light conducting fiber elements, located at equally spaced intervals about the image forming device, have image forming end portion axes which are parallel with the common image forming end portion axis. Four of the illumination light conducting fiber elements, located at equally spaced intervals about the image forming device, and at equally spaced intervals between the first four illumination light conducting elements, have image forming end portion axes which are at a 10 degree angle to the common image forming end portion axis. The remaining eight of the illumination light conducting fiber elements, located at equally spaced intervals about the image forming device, have image forming end portion axes which are at a 20 degree angle to the common image forming end portion axis. Each illumination light conducting fiber element has a polished end face generally normal to its image forming end portion axis.
Other objects, advantages and aspects of the invention will become apparent upon perusal of the following detailed description and claims and upon reference to the accompanying drawings.